SAINT PAUL, Minn. -- A new study by the University of Minnesota's Center for Applied Research and Educational Improvement has added fuel to arguments for later start times from high schools. The three-year study involved 9,000 students at eight high schools in three states.
Previously, studies at Edina and Minneapolis showed later start times and, thus, more sleep, had produced higher graduation rates. This new study, also funded by the Centers for Disease Control (CDC), went much farther, into grades and standardized test results.
"We did find that there was statistically significant improvement in their grades in English, math, social studies and science, all the core academic areas," said Kayla Wahlstrom, Ph.D. Director of the University of Minnesota Center and author of the study. "And we found improvements on standardized tests, like the ACT test."
In 1996, Edina became one of the first districts in the nation to try later start times for the High School. Minneapolis followed in 1997. The study released Wednesday studied students from five Minnesota schools (St. Louis Park, Mahtomedi, Woodbury, Park and East Ridge), two from Colorado (Boulder and Fairview) and one, Jackson Hole, in Wyoming.
The study showed that schools with start times at 7:30 a.m. had just 34 percent of students who reported getting eight or more hours of sleep. However, schools with start times as late as 8:55 a.m. had 66 percent of students obtaining eight or more hours of sleep.
"Earlier studies that have been done by the CDC, had found that eight hours seems to be the 'tipping' point for students in terms of the choices they make," said Wahlstrom. "This study is important because it finds the link between teenagers getting eight hours of sleep at the minimum and positive outcomes."
The study found that in the Wyoming district, the 8:55 a.m. start time resulted in a 70 percent drop in car crashes involving teen drivers.
"How fast do they brake? Are they watching in their rear view mirror? Are they keeping apprised of what is going on around them? Students that are sleep deprived have much less capability of managing all the pieces that go into us who have been driving for years," said Wahlstrom. "Teens are novice drivers and the do not think about all these things."
Wahlstrom explained that teenagers' body clocks normally do not allow them to fall asleep until 10:45 or 11:00 p.m. Sending them to bed earlier does not necessarily translate to more sleep. Studies indicate that teens rise, on average, about 54 minutes before leaving for school.
"If you have a 7:10 or 7:15 start," said Wahlstrom, "you are getting up at 6:30 or 6:15."
The effect, according to Wahlstrom, is stealing sleep time from the teenagers. A common objection to later start times comes from coaches who fear cutting into sports practice times at the end of the school day. However, Wahlstrom said coaches she spoke with found that the athletes were more able to remember plays and could perform better physically with more sleep.